What is the principle of exchange of gases in respiratory organs?

The principle of gas exchange in respiratory organs, such as the lungs in mammals, is based on the process of diffusion. Oxygen from inhaled air diffuses across the thin walls of alveoli into the bloodstream, where it binds to hemoglobin in red blood cells. Simultaneously, carbon dioxide, a waste product of metabolism, diffuses from the blood into the alveoli to be exhaled. This exchange is driven by concentration gradients, with gases moving from areas of higher concentration to areas of lower concentration.